Polyalkylsubstituted cyclopentadienes are useful as monomers and in forming metallocenes of transition metals. Such metallocenes are useful components of olefin polymerization catalysts, as is known in the art. U.S. Pat. No. 5,329,056 discloses the preparation of substituted cyclopentadienes, including 1,2,3,4-tetramethylcyclopentadienes starting with a vinyl ketone and a vinyl halide. The pyrolysis of isobornyl acetate to yield mixtures containing 1,2,3- and 1,2,4-trimethylcyclopentadienes has been reported by De Haan et al., Rec. Trav. Chim. (1968), 87, 289-297. The pyrolysis of 1,4,5,5-tetramethylcyclopentadiene, prepared in low yields from methylcyclopentadiene to form 1,2,3,4-tetramethylcyclopentadiene has been reviewed in Mironov et al., Russ. Chem. Rev. (1981), 50, 666-679.